Oil well heating method and apparatus



April 5, 1955 R. R. WATERMAN 2,705,535

on. WELL HEATING METHOD AND APPARATUS Filed June 24, 195o 2 shets-sheet1 N V EN TOR. #K9/arman BY A April 5, 1955 R. R. WATERMAN OIL WELLHEATING METHOD AND APPARATUS 2 Sheets'heet 2 Filed June 24, V1950 IN1/ENTOR Mferma/v United States Patent O OIL WELL HEATING METHOD ANDAPPARATUS Russell R. Waterman, Lodi, Calif. Application .lune 24, 1950,Serial No. 170,116 16 Claims. (Cl. 1166-40) This invention relatesgenerally to heaters suitable for use in oil wells. sirable to supplyheat in a zone well below the normal oil level in the well in order tofacilitate proper liow of oil from an oil producing strata. Apparatusused in the past for this purpose has not been satisfactory,particularly when applied to the deeper producing wells. Hot waterheaters are subject to excessive heat losses and do not make available asufficient amount of heat in the region where it is desired. In additionhot water heaters require considerable equipment to supply the hot waterin the amounts desired. Steam heaters which have been used in the pasthave not been satisfactory particularly because it has been difficult orimpossible to maintain live steam in the heating jacket. When a heaterof this character becomes filled with condensate the efficiency andperformance is greatly impaired.

It is a general object of the present invention to provide a novelmethod for heating oil producing wells. The present method ischaracterized by maintenance of live steam within the heating jacket,whereby maximum heating effect is secured in the region where the heatis desired.

A further object of the invention is to provide novel heating apparatusfor oil producing wells, and which in particular will be relativelyetlicient and of high capacity, and will enable adequate heating tofacilitate oil production and proper pumping.

Additional objects and features of the invention will appear from thefollowing description in which the preferred embodiments have been setforth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 illustrates a heater incorporating the present invention andinstalled in an oil producing well.

Figure 2 is a side elevational detail in section illustrating thecontrol orifice employed in the heater of Figure l.

Figure 3 is a side elevational view in section illustrating amodilication of Figure 1.

Figure 4 is an enlarged cross-sectional detail illustrating the flowcontrolled orifice incorporated in Figure 3.

Referring to Figure 1, I have shown an oil producing well having theusual casing 10, and which has been equipped with the pumping tube 11.The lower end of the tube 11 connects with the barrel of a suitablepumping apparatus, such as one of the sucker rod type. According tocustomary practice the pump barrel is installed well below the normaloil level, and the plungers of the pumping apparatus connect with thesucker rod 12, which is reciprocated by suitable apparatus located atthe surface of the well.

Well below the normal oil level I provide a heating jacket 13, which canbe cylindrical in form and arranged to embrace a section 11a of thetubing. The upper end of the jacket is connected with a steam supplypipe line 14. This pipe line extends to the surface of the well where itis connected with a suitable source of steam under pressure. For thispurpose I prefer to use a high pressure boiler of the ash type. Suitablesteam ilow indicating means is also connected to the pipe line 14 at thesurface of the well. Thus I have shown a metering orifice 16, which canbe used in conjunction with the pressure gauges 17 and 18, to indicatethe rate of steam ilow.

A condensate pipe line 19 also connects with the jacket 13, and extendsupwardly to a point above the normal In many oil producing wells it isde- 2,705,535 Patented Apr. 5, 1955 oil level. A downwardly Iturned pipeportion 21 is shown connected to the upper end of pipe line 19, and thepipe line is also shown provided with a check valve 22 to preventbackflow of oil from the well.

The lower end of the condensate pipe line 19 connects with an oricefitting 23 (Figure 2) which is located near the lower end of the jacket.This fitting forms a ilow restricting orifice 24, which communicateswith the interior of the jacket through the screen or strainer 26.

The jacket 13 can be installed either above or below the cylinder of thepumping apparatus. As illustrated it is assumed that the tube section11b forms the pumping cylinder of a suitable oil well pump. Thenecessary plungers and valves (not shown) of the pumping apparatus areinstalled in the cylinder 11b.

Operation of the apparatus described above, and the steps of the presentmethod are as follows: In a typical instance the oil producing stratamay be at a distance of say 1,000 feet from the surface of the Well, andthe normal oil level may extend to say 300 feet above the producingstrata, or about 700 feet below the surface. With such an installationthe boiler should be capable of supplying steam at a pressure of theorder of 275 to 300 p. s. i., and at a rate suicient to supply theheater requirements. The pipe 19 can have its upper end terminatingabout feet above the normal lluid level, or about 600 feet below the topof the Well. When steam is rst applied to the pipe line 14, all of it iscondensed, and condensate accumulates in the jacket 13. As pressurebuilds up in the jacket the condensate flows through the orifice 24 andupwardly through the line 19, to be discharged into the well above thenormal oil level. Assuming that the steam pressure and the steam supplyare adequate, a condition is soon reached in which the condensate levelfalls to about the region of the orilice 24, and thereafter the oricepasses steam together with all of the condensate. This condition isimmediately observed by the operator by noting the pressure gauges 17and 18. When steam starts to flow through the orifice 24 the steamconsumption drops sharply, steam ow through the pipe line 14 is reduced,and. this is indicated by a sharp drop in the pressure differentialbetween gauges 17 and 18. The apparatus is now functioning normally, andheat is eiciently transferred from steam through the walls of the jacket13 to the surrounding oil. It is also transferred to the tubing 11, andto oil passing through the same. By occasional checking of the pressuregauges 17 and 18, the operator can make certain that the jacket isoperating properly, and that live steam is being delivered to the jacket13, for proper performance. The condensate delivered through the line 19also transfers some heat to the surrounding oil, and the condensatedischarged into the well from this line is hot water, which intermingleswith the oil and likewise transfers some effective heat. Since thecondensate line 19 is not extended to the surface of the deeper wells towhich the invention yis particularly applicable, the pressure requiredto discharge condensate through the same is not excessive, and thereforean applied steam pressure of reasonable value can sufce to dischargecondensate through the orifice 24 and pipe 19, and to overcome the flowresistance involved.

In the embodiment of the invention illustrated in Figures 3 and 4, theheater jacket 31 surrounds a section 32a of the pump tubing, and theheater is located below the barrel 32h of the pumping apparatus. Tubesection 32a connects with a cross tube 33, which communicates with theexterior of the jacket on opposite sides of the same. The steam pipeline 34 connects with the upper part of the jacket, and the lower partof the jacket connects with a condensate line 36, through the orificecontrol device 37. Device 37 can be constructed as shown in Figure 4. Itconsists of a body 38 having an inner chamber 39 which is incommunication with the lower inlet 41. An open or inverted bucket typeiloat 42 is loosely and pivotally supported at 43 from the free end ofthe valve lever 44. This lever carries a hernispherical valve member 45,which cooperates with the valve seat 46. It is loosely retained by thedepending rods 47 and is provided with upturned tabs 48 which engage andfulcrum upon the shoulder face 49. The

passage 51 through the seat 46 is in communication with the condensateline 36. The lever 44 carries a button or stud 52 which is adapted toengage the tab 53. It will be evident that when the bucket assumes alower position the valve member 45 is open with respect to the seat.However when the bucket lifts, tab 53 presses upwardly upon the stud 52,to move the valve member to closed position relative to the seat.

The device 37 is constructed the same as an inverted bucket type steamtrap, such as a trap of the type manufactured and sold under the tradename of Armstrong Operation is as follows: When the chamber 39 is filledwith condensate the bucket assumes its lowermost position whereby thevalve member 45 is open relative to the seat 46. Assuming now thatcondensate flows through the inlet 41, it is permitted to ow through theseat 46 and upwardly through the condensate line 36, without substantialrestriction. When some steam enters the chamber 39 together withcondensate, the steam initially tends to accumulate within the bucket,thus lending some buoyancy which tends to lift the bucket to move thevalve member 45 toward closed position. Thus the positioning of thebucket is dependent upon the buoyancy imparted by presence of steamwithin the same, and this in turn serves to automatically control thepositioning of the valve member 45, as in a steam trap. With such adevice the orifice through the seat 46 is automatically restricted asthe steam to condensate ratio of material entering the inlet 41increases. Conversely as the steam to condensate ratio of materialentering inlet 41 decreases, the valve member 45 automatically movestoward open position, to decrease the fiow restriction through theorifice 51.

In place of the particular device 37 which has been illustrated anddescribed, I can employ other devices for automatic orifice control, asfor example other types of bucket or float operated steam traps.

In order to provide a suitable mounting for the control device 37, it isshown clamped against the lugs 56 of the web 57, with its lower endseated within the tubular strainer 58. This strainer extends between thedevice 37 and the lower end cap 59 for the heater.

Except for operation of the control device 37, the apparatus of Figure 3operates in substantially the same manner as Figure l. Automaticreduction of the effective cross-sectional flow area which is madepossible by the ow control valve 47, tends to increase the change in thereading of pressure gauges 17 and 18 when a condition of normaloperation is attained, as distinguished from the higher steam flow ratesexperienced when the apparatus is first being placed in operation.

It will be evident from the foregoing that I have provided an oil wellheater which is capable of providing the desired amount of heat withinthat region of the well where the heat is desired, and where it will beof maximum effectiveness. An operator can make certain that live steamis being delivered to the heating jacket, and this condition can bemaintained as long as it may be desired. The dumping of hot watercondensate into the well from the condensate line 19 improves ratherthan impairs the effectiveness of the apparatus, due to the added heatwhich is supplied. The amount of this condensate is ordinarily smallcompared with the oil produc ing capacity of the well, and this water iseventually pumped out of the well together with the oil.

I claim:

l. A continuously operable bottom hole heater for oil wells comprising aheat transfer jacket having a closed chamber therein and an exteriordiameter less than the interior diameter of an oil well casing in whichthe heater is to be used, said jacket being adapted to be positioneddeep in the casing and adjacent an oil producing subsurface strata, aseparate heating fluid supply line adapted to extend from ground levelto said chamber, and a combined condensing and removal passage meansbetween the chamber and the interior of the casing removed from thesupply line, means forming a flow restricted orifice between the chamberand the inner end of said condensing and removal passage means andhaving a fixed area smaller than the cross-sectional area of the chamberand smaller than the cross-sectional area of the removal passage means,said orifice being at a level adjacent the bottom of the chamber, saidfixed orifice having a capacity for passing condensate only slightly inexcess of one capable of discharging all said condensate from thechamber, and a substantially free flow discharge opening at the outletend of said removal passage means.

2. A bottom hole heater for oil wells comprising a heat transfer jackethaving a chamber therein closed to the fiow of production liuid and anexterior diameter less than the interior diameter of an oil well casingin which theheater is to be used, said jacket being adapted to bepositioned deep in the casing and adjacent an oil producing sub-surfacestrata, a separate heating fluid supply line adapted to extend from theground level to said chamber and forming the only passage into saidchamber, a spent heating fluid removal pipe adapted to extend between alower part of the chamber and a fixed location above the chamber, ahydraulic flow restricting orifice adjacent the bottom of the chamberforming the only passage from the interior of the chamber to theexterior and comprising a passage between the chamber and the removalpipe, said flow restricting orifice having a fixed area smaller than thecross-sectional area -of the chamber and smaller than thecross-sectional area of the removal pipe, and a free flow dischargepassage at the upper end of the removal pipe.

3. In an oil well heating system the combination of a casing extendinginto the well to a location below production fluid level, a pump line inthe casing extending to a location below said fluid level and a bottomhole heater comprising a heat transfer jacket having a chamber thereinclosed to the flow of production fiuid and having an exterior diameterless than the interior diameter of an oil well casing in which theheater is to be used, said jacket being adapted to be positioned deep inthe casing leaving a clear space between the jacket and the casing andadjacent an oil producing sub-surface strata, a fluid supply line ofcross-sectional area small relative to the cross-sectional area of thechamber adapted to extend from the ground level to the chamber, saidsupply line being separate from the pump line and lying between the pumpline and the interior wall of the casing, a spent fluid removal pipeadapted to extend between the chamber at a location adjacent the bottomand a fixed location above the chamber, a constantly open restrictedorifice adjacent to but removed from the bottom of the chamber forming apassage between the chamber and the lower end of the removal pipe, saidrestricted orifice having a fixed area smaller than the cross-sectionalarea of the removal pipe and smaller than the cross-sectional area ofthe chamber and adapted to admit discharge of said condensate, saidrestricted orifice being adapted to determine the depth of a condensatereservoir at the bottom of the chamber, and a free fiow dischargepassage at the upper end of the removal pipe substantially greater inarea than the restricted orifice.

4. A bottom hole heater for oil wells comprising a heat transfer jackethaving a chamber therein for condensate and an exterior diameter lessthan the interior diameter of an oil well casing in which the heater isto be used, said chamber being closed to the ow of production liuid,said jacket being adapted to be positioned deep in the casing leaving aclear space between the jacket and the casing and adjacent an oilproducing sub-surface strata, a separate fluid supply line for heatingfluid only and of cross-sectional area small relative to thecrosssectional area of the chamber, said supply line being adapted toextend from the ground level to the upper portion of said chamber, acondensing and removal pipe of small cross-sectional area compared tothe chamber adapted to extend between the lower end of the chamber and afixed location above the chamber and above the strata a distancesufficient to allow free outflow of condensate, a restricted orificeadjacent the bottom of the chamber forming an outlet from the chamber tothe removal pipe, said restricted orifice having a fixed area sufficientto pass slightly more than all said condensate and having a locationabove the chamber bottom adapted to determine the depth of a condensatereservoir at the bottom of the chamber, and a free flow dischargeorifice at the upper end of the removal pipe substantially greater inarea than the removal pipe.

5. A bottom hole heater for oil wells comprising a heat transfer jackethaving a chamber therein for condensate and an exterior diameter lessthan the interior diameter of an oil well casing in which the heater isto be used, said jacket being adapted to be positioned deep in thecasing leaving a clear space between the jacket and the casing andadjacent an oil producing subsurface strata, a hot fluid supply line ofdiameter small relative to the diameter of the chamber adapted to extendfrom the ground level to the upper portion of said chamber, said linehaving a pressure differential gage therein above said ground level, acondensate removal pipe of diameter small compared to the chamberadapted to extend vertically at one side of the jacket and between alower part of the chamber and a fixed location above the chamber andabove the strata a distance sufficient to allow free outflow ofcondensate, a restricted orifice above the bottom of the chamber forminga passage from the chamber to the lower end of the removal pipe, saidrestricted oritice having a fixed area sufficient to pass all saidcondensate plus a small percentage of hot fluid and adapted to determinethe depth of a condensate reservoir at the bottom of the chamber, a freeflow discharge orifice at the upper end of the removal pipesubstantially greater in area than the restricted orifice, a passagevertically through the jacket from a point below the bottom of thechamber to the ground level adapted to pass a mixture of oil landcondensate to said ground level, and a back chefk valve in said removalpipe adjacent the discharge ori ce.

6. A method of continuously heating oil wells during pumping forextraction of low gravity oil by use of a closed heating chambercomprising lowering the chamber into a well to a level adjacent an oilproducing strata, passing live steam from the ground level down into thechamber at a relatively rapid rate such that the quantity of steamexceeds the amount thereof reduced to condensate and simultaneouslyventing the condensate through a discharge outlet to the interior ofsaid casing at a point adjacent said oil producing strata, said ventingfrom the chamber being at a lower portion thereof and at a fixedpredetermined rate restricted to one very slightly exceeding the rate ofaccumulation of said condensate and continuing supplying live steamuntil some live steam is being vented from the chamber with thecondensate, and then changing the rate of supply of live steam to a ratewhere a balance is maintained between the amount of steam supplied andthe amount of steam condensed and condensing all the steam escaping withthe venting of the condensate so that no steam passes into the well.

7. A method of continuously heating oil wells during pumping forextraction of low gravity oil by use of a heating chamber closed againstflow of production fluid comprising lowering the chamber into a well toa level adjacent to and below the top of an oil producing strata,passing live steam from the ground level down into the chamber at arelatively rapid rate such that the quantity of steam exceeds the amountthereof reduced to condensate in the chamber and during passagethereinto and simultaneously venting the condensate from the chamber ata restricted rate to a free-flowing discharge outlet at a level abovethe top of the strata and below ground level, said venting from thechamber being at a lower portion thereof and at a fixed predeterminedrate restricted to one approximately equal to the rate of accumulationof said condensate and continuing supplying live steam until some livesteam is being vented with the condensate, then reducing the supply oflive steam to a rate sufficient to balance the rate of condensation,condensing all the steam which is vented with the condensate and beforedischarge of the condensate into the well and finally pumping oil andcondensate from the well past the heating chamber through a separatepump line while the reduced rate of live steam is being maintained tomaintain the heating condition.

8. A bottom hole heater for oil wells extending to oil producing strata,comprising a heat transfer jacket having a chamber therein closed to theflow of oil, an independent steam supply line adapted to extend fromground level to the level of said strata and being adapted to beconnected to the chamber, said jacket being adapted to be located deepin a well adjacent the level of oil producing strata, and an orificefitting adjacent the bottom of the chamber and between the chamber andthe exterior of said jacket, said fitting including a transversepartition and having a flow-restricting orifice through the partition,said orifice having a capacity sufiicient for passing simultaneously allthe condensate resulting from the condensation of steam passed throughsaid supply line to the chamber together with a quantity of steam notexceeding in weight more than a small fraction of the weight of CIK allthe condensate, an elongated condensing line extending from the orificeto the interior of the casing and a free flow discharge passage at theouter end of the condensing line.

9. A bottom hole heater for oil wells extending to oil producing strata,comprising a heat transfer jacket having a chamber therein, said chamberbeing closed to the flow of production fluid from the well, anindependent steam supply line from ground level tot the level of saidstrata and being connected to the/ jacket, an elongated verticallyextending condensing and removal pipe having an inlet end at the bottomof the pipe communicating with the chamber at the bottom of the chamber,and an orifice fitting between the chamber and the inlet end of theremoval pipe, said fitting including a transverse partition'and having aflow restricting orifice through the partition having a maximumeffective cross-sectional area less than the area of the removal pipe onthe outlet side of the orifice, said orifice having a capacity sufcientfor passing simultaneously all the condensate resulting from thecondensation of steam passed through said supply line to the chambertogether with a quantity of steam not exceeding in weight more than asmall fraction of the weight of all the condensate, said removal pipehaving a condensing portion thereof between the orifice and the outlet,said outlet being in direct communication with the interior of the well.

l0. A continuously operable bottom hole heater for oil wells wherein acasing has been sunk to oil producing strata, comprising a heat transferjacket having a chamber therein adapted to be located in the wellthroughout the depth of the strata, a separate steam supply line fromground level to the level of said strata, said steam supply line beingadapted to be connected at its lower end to the chamber, a verticallyextending condensate removal pipe having an inlet at the bottom endcornmunicating with the chamber at the bottom of the chamber, said pipehaving a length extending beyond the jacket, and an orice fittingbetween the chamber and the inlet end of the removal pipe, said fittingincluding a transverse partition and having a flow-restricting orificethrough the partition, said orifice having a capacity sufficient forpassing simultaneously all the condensate resulting from thecondensation of steam passed through said supply line to the chambertogether with a quantity of steam not exceeding in weight more than asmall fraction of the weight of all the condensate, and a substantiallyfree flowing discharge opening at the outlet end of the removal pipe.11. A bottom hole heater for oil wells wherein a casing has been sunk tooil producing strata and a continuously operable pump line has beenextended into the casing, said heater being continuously operable duringpumping operations and comprising a heat transfer jacket having achamber therein for heating fluid only, a steam supply line from groundlevel to the level of the strata, said supply line being connected atits lower end to the upper portion of the jacket whereby to positionsaid jacket deep in the well adjacent tlie oil producing strata, avertically extending condensing and removal pipe hav-ing an inlet endcommunicating with the chamber at the bottom of the chamber, said pipehaving a length extending through and beyond the jacket, and an orificefitting between the chamber and the inlet end of the removal pipe, saidfitting including a transverse partition and having a flow-restrictingorifice through the partition of cross-sectional area smaller than thearea of the removal pipe on the outlet side of the orifice, said orificehaving a capacity sufficient for passing simultaneously all thecondensate resulting from the condensation of steam passed through saidsupply line to the chamber and passing into the chamber together with aquantity of steam not exceeding in weight more than a small fraction ofweight of all the condensate passing said orifice, and a substantiallyfree flowing discharge opening at the outlet end of the removal pipe,said discharge opening being in direct communication with the interiorof the casing and at a level above the level of the oil producingsubsurface strata.

l2. A continuously operable bottom hole heater for oil wells havingcasings and pump lines extending to oil producing strata comprising aheat transfer jacket having a chamber therein, a steam supply lineseparate from the pump line adapted to extend from the ground level tothe level of said strata and adapted to be connected at its lower end tosaid chamber, said jacket being adapted to be located deep in a welladjacent the level of the strata and to retain steam and condensate, anorifice fitting between the chamber adjacent the bottom thereof and theexterior of the jacket, said fitting including a transverse partitionand a How-restricting orifice device through the partition, said orificedevice having an opening therethrough, a seat around said opening, anorifice restrictor adapted to engage said seat in a position at leastpartially closing said opening and a oat in the chamber having a greaterbuoyancy in the presence of steam than in the presence of condensatealone, said oat being operably attached to the restrictor and therestrictor being responsive to movement of the float for moving todifierent positions with respect to the seat and the opening whereby anincrease in the proportion of steam to condensate is adapted to diminishthe effective area of the opening.

13. A continuously operable bottom hole heater for an oil well having acasing and a pump line therein extending to oil producing stratacomprising a heat transfer jacket having a chamber therein, a steamsupply line adapted to extend from the ground level to the level of saidstrata and adapted to be connected at its lower end to said chamber,said jacket being adapted to be located deep in a well adjacent thelevel of the strata and to retain steam and condensate therein, anorifice fitting between the chamber at the lower end thereof and theexterior of the jacket, said fitting including a transverse partitionand a dow-restricting orifice device through the U partition, saidorifice device having an opening therethrough, a seat around saidopening, an orifice restrictor adapted to engage said seat in a positionat least partially closing said opening and a float in the chamberhaving a greater buoyancy in the presence of steam than in the presenceof condensate alone, said float being operably attached to therestrictor and the restrictor being responsive to movement of the floatfor moving to different positions with respect to the seat and theopening whereby an increase in the proportion of steam to condensate isadapted to diminish the effective area of the opening, and a condensingand removal line connected between the downstream side of the orificeand the interior of the well below ground level.

14. ln the heating of oil wells for extraction of low gravity oil by useof a closed heating chamber having a supply line thereto, a vent fromthe lower end of the chamber to the interior of the casing and aHow-restricting orifice in said vent the method comprising lowering thechamber to a level adjacent oil producing strata, initially passing livesteam from ground level through the supply line into the chamber at aselected rate until the quantity of steam supplied exceeds the amountcondensed by the initial heating of the well and contents, andsimultaneously venting the condensate into the casing through saidorifice until the condensate is vented at a rate more rapid than 4it isformed and a quantity of steam escapes through the orifice at a lesserrute than the steam is supplied. then continuing supplying steam at asteady rate such that the amount of heat supplied by the steam balancesthe amount of heat absorbed by the well and condensing steam escapingfrom the orifice before the steam reaches the interior of the casing sothat only condensate is discharged into the casing.

15. ln the heating of oil wells for extraction of low gravity oil by useof a closed heating chamber having a supply line thereto, aflow-restricting orifice therefrom adjacent the bottom of the chamberand a vent pipe extending from the orifice to the interior of the casingwhereby low gravity oil therein is rendered less viscous so as toincrease the rate of flow the method comprising lowering the chamber toa level adjacent oil producing strata, Iinitially passing live steamfrom ground level into the chamber at a selected rate until the quantityof steam supplied exceeds the amount condensed by the initial heatingot' the steam line, chamber, well and contents, simultaneously ventingthe condensate through the flowrestricting orifice into said vent pipeand continuing the supply of steam until the condensate is vented at arate more rapid than yit is formed and a quantity of steam escapesthrough the orifice at a lesser rate thanV the steam is supplied, thencontinuing supplying steam at a rate only slightly exceeding the rate atwhich steam is condensed by an amount such that the amount of heatsuppiied by the steam balances the amount of heat absorbed by the welland wherein excess escaping steam is reduced to a rate no faster thanthe vent pipe is capable of condensing and only condensate is ventedinto the well.

16. In the heating of oil wells for extraction of low gravity oil by useof a closed heating chamber having'a supply line thereto, a vent pipeextending therefrom at the bottom of the chamber and to the interior ofthe casing and a flow-restricting orifice at an inlet end of the ventpipe the method comprising lowering the chamber to a level adjacent oilproducing strata, initially passing live stream from ground level intothe lowered chamber at a selected rate until the quantity of streamsupplied exceeds the aggregate amount condensed by the initial heatingof the steam line, the chamber, the well and contents, venting thecondensate during the initial heating into the casing through saidorifice until the condensate is vented at a rate more rapid than it isformed and a quantity of steam escapes through the orifice, effectingVreduction of the capacity of the orifice and then reducing the quantityof steam supplied to a rate exceeding the rate of condensation but by anamount such that the steam pressure in the chamber remains substantiallyconstant, whereby the amount of heat supplied by the steam balances theamount of heat absorbed by the well, and finally effecting condensing ofany steam in the vent pipe which escapes through the orifice to saidvent pipe whereby only condensate is vented into the well.

References Cited in the file of this patent UNITED STATES PATENTS 48,994Parry July 25, 1865 200,393 Harris Feb. 19, 1878 403,183 Firth May 14,1889 760,304 Butler May 17, 1904. 1,012,777 Wigle Dec. 26, 19111,709,581 Johnson Apr. 16, 1929 1,714,647 Vaughn May 28. 1929 1,960,999Kaye May 29, 1934 2,035,381 Abele Mar. 24, 1936 2,049,050 Cram July 28.1936 2,094,038 Kernin Sept. 28, 1937 2,208,784 Armstrong July 23, 1940

